HDP301 Cardiac Muscle Cells Essay

HDP301 Cardiac Muscle Cells Essay

HDP301 Cardiac Muscle Cells Essay

HDP301 Cardiac Muscle Cells Sample Essay

Muscle cells, also called myocytes, are the cells that compose the muscle tissue. The human body primarily has three types of muscle cells: skeletal, cardiac, and smooth muscle cells. Each muscle cell has unique characteristics suited to its function. The purpose of this paper is to describe cardiac muscle cells and discuss the pathology that occurs when the cell stops functioning normally.

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Section 1: Description of Cardiac Muscle Cells

Cardiac muscle cells, also known as cardiomyocytes, are the muscle fibers that comprise the myocardium, the middle muscular layer of the heart. They compose the heart’s thick middle layer and are surrounded by a thin outer layer known as the epicardium and an inner endocardium (Nusier et al., 2021). Sweeney & Hammers (2018) explain that cardiac muscle cells  are branched cylinders, usually 100–300 mm in length and 20 –30 mm in width. However, they can hypertrophy to a width of up to 150–200 mm. In addition, they have a single nucleus, unlike skeletal muscles, which are multinucleated. Cardiomyocytes are referred to as striated muscles, since the filaments of actin and myosin that provide energy for their contraction are arranged in repeating arrays, called sarcomeres, which have a striated appearance on microscopy.

Cardiomyocytes typically have the same cell organelles as skeletal muscle cells but have more sarcomeres. Sarcomeres are the essential contractile units of cardiomyocytes. They are made up of thick and thin filaments, vital for generation and transmission of mechanical force needed to pump blood. The multiple sarcosomes supply the cells with the energy needed for contraction (Sweeney & Hammers, 2018).

Cardiac muscle cells are structurally joined by intercalated discs, which contain gap junctions to allow diffusion and communication. The intercalated discs appear like dark bands between cells, which are a unique characteristic of cardiomyocytes. The thin and thick myofilaments overlap each other within the sarcomere of the cell, creating a striated appearance (Sweeney & Hammers, 2018). The outer surface of the cardiac muscle cell is enclosed by a plasma membrane called the sarcolemma that creates a barrier between intracellular and extracellular contents. Kitmitto et al. (2019) explain that the structural integrity of the sarcolemma is vital for promoting cardiac contraction by forming microdomains like the caveolae, t-tubular network, and the intercalated disc.

The primary role of cardiac muscle cells is to produce enough contractile force for the heart to pump blood efficiently through the circulatory system. The cardiomyocytes contract together uniformly, producing enough pressure to force blood to all the body parts (Nusier et al., 2021). The cardiomyocytes’ rapid, involuntary contraction and relaxation are crucial for pumping blood throughout the circulatory system.

The cardiac muscle cell is unique in that it has autorhythmicity. It differs from skeletal and smooth muscle cells, which usually need neural input for contraction. Cardiomyocytes have their own pacemaker cells, like the sinoatrial (SA) node, that depolarize on impulse (Nusier et al., 2021). The depolarizations happen consistently, but the pacemaker cells can receive input from the autonomic nervous system to reduce or elevate the heart rate based on the body’s requirements. Nusier et al. (2021) also explain that calcium ions release and uptake stimulate the cardiac cells to promote cardiac contraction and relaxation. Calcium ions are involved in cardiac contraction, heart function, and metabolism.

Section 2: Pathology

Cardiac muscle cells cannot divide effectively. Thus, the cardiac cells cannot be replaced if they get lost. Consequently, each cardiomyocyte must work harder to generate the same cardiac output. Cardiomyocytes can hypertrophy if there is an increased body demand for increased cardiac output. This results in impaired cardiomyocyte relaxation and inflammation. Damage to cardiomyocytes results in inappropriate cardiac contractility (Schwinger, 2021). Cardiomyocytes have a low regenerative potential and injury or insult to cardiac muscle cells can have serious consequences. In the event of a heart attack, the injured area heals, and a scar replaces the original tissue. This causes a loss of contractile myocardium due to scar tissue’s inability to contract.

Dysfunction of cardiomyocytes is associated with heart failure. When the cardiac muscle cells cannot produce enough contractile force, the myocardium develops structural and functional defects, which causes impairment of ventricular filling and systolic ejection of blood (Schwinger, 2021). Heart failure is characterized by a marked acute or chronic loss of cardiomyocyte, which causes systolic dysfunction. Besides, marked remodelling of these sarcolemma microdomains contributes to the development and progression of heart failure (Kitmitto et al., 2019). Furthermore, the reduced blood supply to the cardiomyocytes causes cell death, cardiac fibrosis, and enlargement and dilation of the left ventricle leading to Ischemic cardiomyopathy.

Conclusion

Cardiac muscle cells make up the myocardium. They are branched cylinders, have a single nucleus, and communicate through intercalated discs. The role of cardiac muscle cells is to produce enough contractile force for the heart to pump blood efficiently through the circulatory system. Increased body demand for blood leads to hypertrophy of cardiac muscles to increase cardiac output and eventually causes heart failure. Damage to cardiomyocytes causes inappropriate cardiac contractility leading to impaired circulation.

References

Kitmitto, A., Baudoin, F., & Cartwright, E. J. (2019). Cardiomyocyte damage control in heart failure and the role of the sarcolemma. Journal of muscle research and cell motility, 40(3-4), 319–333. https://doi.org/10.1007/s10974-019-09539-5

Nusier, M., Shah, A. K., & Dhalla, N. S. (2021). Structure-function relationships and modifications of cardiac sarcoplasmic reticulum Ca2+-transport. Physiological research, 70(Suppl4), S443–S470. https://doi.org/10.33549/physiolres.934805

Schwinger, R. H. G. (2021). Pathophysiology of heart failure. Cardiovascular diagnosis and therapy, 11(1), 263–276. https://doi.org/10.21037/cdt-20-302

Sweeney, H. L., & Hammers, D. W. (2018). Muscle Contraction. Cold Spring Harbor perspectives in biology, 10(2), a023200. https://doi.org/10.1101/cshperspect.a023200

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HDP301 Assignment: The Cell

TOPIC FOR THIS ASSIGNMENT: CARDIAC MUSCLE CELLS

INSTRUCTIONS ARE BELOW

Cells can be described as the first level in an organism that exhibit the characteristics of life (reproduction, movement adaptability etc.). This semester we (will be) have discussed many cells with respect to their primary responsibility within a system. It is easy to think of an osteoblast as just a cell that produces bone tissue or a muscle cell that just is responsible for generating tension by shortening but it would be a mistake. We know these cells have 100s to 1000s of receptors imbedded in their membranes that specifically respond to ligands that will influence cell function. Historically, the focus of cell or chemical messenger function was limited to its primary function. We also should be aware of any other functions and responsibilities these cells often have in addition to their primary function. Finally, you should discuss any pathologies that occur when this cell is unable to function within its homeostasis. This assignment is designed to illustrate the primary function(s) of a cell and what sorts of environmental factors (or signals) they are responsible for or respond to and secondly, what happens when it is unable to do so. This understanding of multiple roles or functions of a cell will lead us to better evidence-based descriptions and explanations for normal health and wellness as well as treatment protocols and outcomes that are more successful for our patients.

Consider this: Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a human organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover. Some differentiation occurs in response to antigen exposure. Differentiation dramatically changes a cell’s size, shape, membrane potential, metabolic activity, and responsiveness to signals. These changes are largely due to highly controlled modifications in gene expression and are the study of epigenetics. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. Thus, different cells can have very different physical characteristics despite having the same genome.

This assignment is designed to illustrate the importance of different/specialized cells in the human body and the potential effects of any one of these cells on health and pathology.

You can work in pairs or as an individual.

Write your paper in APA format. Use at least 3 primary peer-reviewed scientific sources. Websites like Wikipedia, Cleveland Clinic or WebMD do not count as references, but they may be good places for you to look for suggestions on important papers that have been published. Please refer to Seneca’s Library Pages if you need help with citations, writing and academic integrity:

https://library.senecacollege.ca/citingsources

https://library.senecacollege.ca/appliedresearch/writing

 

This assignment is broken into two sections.

Cover Page Must include a title, course code and section, the full name(s) of the contributor(s), date of submission

Section 1 – Research and write a description of your chosen cell. Be sure to include a general description of the cell (structure, synthesis and any unique features or properties). You should include the system it is most commonly associated with and its mechanism of action (purpose) within that system. You should discuss and describe additional functions for your chosen cell. Consider and describe what makes this cell behave or function differently from other cells. What influences might make this cell work better or worse (receptors it may have for specific messengers).

Section 2 – In this section, you should discuss and explain the pathology created when this cell stops functioning in a healthy manner -it may over-produce or under-produce a messenger, it may stop responding to messengers. What is the impact of this dysfunction on the system or systems it is associated with. Are there solutions to this dysfunction? What are they?

Make sure to write comprehensively, demonstrating depth of knowledge. Use complete sentences.

Use relevant vocabulary, including anatomical positions, to describe human anatomy and physiology and the role of homeostasis and metabolism in the normal functioning of organ systems where applicable. Apply knowledge of the chemical basis of life and biological processes to explain basic cell structure and function as it relates to the development of tissues and organs in anatomy, physiology and pathophysiology

References

You should discuss your topic with your professor but your paper must be about a cell associated with one of the systems we have discussed this semester:

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Portfolio Grading Rubric

	Levels of Achievement
Criteria	Does not meet expectations (<65%)	Meets minimum expectations (65%)	Exceeds basic expectations (100%)
Completness: Does your response directly answer each part of the assignment question(s)? Does your response directly answer each part of the assignment question(s)?	0 to 18 points One or both sections missing. Introduction unclear and leaves reader with no impression of the paper. and/or conclusion does not provide synopsis of key points	19 to 19 points did enough to meet the minimum requirements	20 to 30 points A very well done assignment. You have expressed knowledge of your subject well and covered the required components of this assignment more than adequately
Knowledge: Does your response clearly show you have read and understand the topic content by correctly using terminology, accurately identifying and/or labeling diagrams and summarizing concepts? Have you made inferences based on this knowledge to scientific or evidence based research?	0 to 18 points missing or marginal analysis lacking engagement with supporting literature.	19 to 19 points acceptable analysis, some evidence of engagement with literature. simple summary of literature, lacking synopsis.	20 to 30 points Concept thoroughly analyzed and supported by literature and personal or professional experience. Including list of defining attributes.
Analysis and References: Have you clearly stated analysis and given examples (when asked) to back them up? Does your response provide analysis to the larger concepts of the topic? Did you use and provide the correct minimum number of references for this topic?	0 to 12 points Missing or minimal attention to detail. Lacking connection.	13 to 13 points Acceptable, however lacking evidence of critical thinking and/or connection to course content.	14 to 20 points Creative, well-constructed, displays evidence of logical relationships, greater than 5 comparisons. Logical connection between the concept map and the analysis of the concept; with reference to it in body of work.
Overall quality of the paper: Did you write clearly, with minimal errors in grammar and spelling? Did you use the APA Method of Citation where needed?	0 to 12 points Unacceptable or poor sentence structure, lacking thought clarity, and unacceptable or largely absent APA formatting, spelling and or grammatical errors.	13 to 13 points Marginal to good writing. Few, grammar, punctuation, formatting and/or APA errors. clear, accurate writing.	14 to 20 points Very good to exceptionally written paper in a clear, accessible, persuasive, and professional language. No grammatical or punctuation errors noted. Paper is formatted in accordance with 6th edition APA manual. No formatting errors noted. Strictly adheres to word count. Five or more Scholarly sources used.